Current Issue : January - March Volume : 2011 Issue Number : 1 Articles : 5 Articles
From the last few years the wireless technology growing exponentially, which is showing a noticeable impact in the field of telecommunications to develop and improve the entire system away from the means of transmission with wires to the without wires (radio frequency) communication. The main problem in wireless environment is deficient bandwidth and time varying channel conditions. The arrival of portable computers, laptops, palmtops and personal digital assistants with incorporated communication capabilities facilitates wireless communication. Quality of service (QoS) is the key problem of today’s wireless communication system because of unending requirements of user. In this paper we will study the requirements, challenges and its possible solutions of QoS in GSM by considering the path loss....
Presently, polymers are playing a significant role in aerospace research world over. However, the use of polymeric materials in primary structures of aerospace is still limited due to the high temperatures encountered by the aerodynamic heating in the case of aerospace. Therefore, thermoplastic materials are often used to replace parts of the engine which are traditionally constructed from metals. PEEK ( poly ether ether ketone) polymer, is increasingly used in the aerospace industry as a replacement for metal components, because it combines all these characteristics with easy processability.This paper mainly deals with the different properties of PEEK and the need for modifying its surface which can further enhance its adhesion characteristics....
Solvomagnetic method is a famous method to get pure crystals of organic or inorganic compounds. In this method with applying a certain strong magnetic field new pure crystal structures can be prepared from original samples. The result will be useful for further complete analysis. In this research some new transition metals salts crystals have been produced by using solvomagneticthis method and their crystal structures have been determined using X-ray diffraction pattern and melting point has also been measured...
The present study aims to investigate the dielectric properties of composites made by reinforcing bagasse as a new natural fibre into a polymer resin matrix. The composites were prepared with varying reinforcement of fibers (i.e., 10%, 15%, and 20%) using epoxy resin as matrix material. Experiments were conducted on the at a temperature range of 40°-160°C and a frequency range of 1 KHz to 1 MHz. The dielectric properties such as dielectric constant, dielectric loss factor of BFRP composites were evaluated as a function of temperature and frequency. Flexural strength, micro hardness of BFRP composite was also evaluated....
The mechanical and thermal properties of the solution-cast films of chemically prepared polyaniline have been studied by means of dynamic mechanical analysis (d.m.a.), differential scanning calorimetry (d.s.c.) and thermogravimetric analysis (t.g.a.). The glass transition temperature (Tg) of the polyaniline films in emeraldine base form was determined and characterized for the first time to be in the range of 105–220°C for the films containing16-0% of 1-methyl-2-pyrrolidinone (NMP) residual solvent, respectively. A critical parameter for a shape memory polymer lies in its shape memory transition temperature. For an amorphous SMP polymer, it is highly desirable to develop methods to tailor its Tg, which corresponds to its shape memory transition temperature. Starting with an amine cured aromatic epoxy system, epoxy polymer were synthesized by either reducing the crosslink density or introducing flexible aliphatic epoxy chains. The thermaland thermomechanical properties of these epoxy polymers were characterized by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). All the crosslinked epoxy polymers with Tg's above room temperature were found to possess shape memory properties. Overall, our approach represents a facile method to precisely tune the Tg of epoxy SMP polymers ranging from room temperature to 89 °C....
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